I would try to get something in there like the dental tool and loosen it. Maybe brake it up into small pieces shop vac'ing with a crevice nozzle at the same time. If that doesn't do it, at least if you could drill some holes in the foam with a long bit to make channels, that could work as well. I think sill pans are most critical with brick veneer and stucco exteriors, probably not so much with lap sidings. If your windows are flashed properly, you might be okay unless you have brick or stucco, then you definetely need a place for moisture and water to channel out over the sill pan.

Your carpenter did a good job given what you have. It looks fine and I'd hesitate to change it. It took me a few replacement windows to figure out what I think works best but it takes ordering the window slightly differently The piece right beside the window lock - going out from the window is called a stile. It's on all four sides of your window. Usually, the depth of the stile can be altered to fit the depth of the wall and then the final trim is attached flush to the wall and with a slight reveal of the stile. Again, the window itself has to be ordered with an extended stile. When you need to match existing window trim, even with an extended stile, there is no way to do the sill correctly... The best "patch" we've found is gray bondo. What we did find is that the manufacturer's stiles can be removed (pella) completely. Then, we just did the normal build out for the sides and top and used "regular" sill that was cut like all the rest of the sills in our house. No extra "layers" or reveals or weird patches. We had to remove the pieces before the windows were installed. I think this only works well when you are completely rebuilding a window opening.

My sink and window set-up are very similar to yours, right down to the window moulding abutting the sides of the cabinets. the only difference is that our sill is much deeper. We have a tall faucet as well. If you're thinking that you need to tile the sill because it will get wet, I can tell you that our sill does not get wet. Don't know why, but it just doesn't. If you want to, you could trim or remove the part of the old sill that sticks out horizontally and use a different piece of painted wood trim applied on its side. By this I mean so its front is flush with the front edge of the moulding on the side of the windows. This is what we did. We have a piece of moulding about 2 inches high and maybe 5/8 inches thick. The side window moulding runs into it. So it's like a frame to the window, but a different profile from the side moulding. It looks like it belongs there. We needed a flat moulding to have room for our faucet. We tiled up to the bottom of the cabinets, and the tile runs into (and stops at) the moulding on the sides and bottom of the window. It looks nice. Sorry I haven't learned how to post pics.

So, I had the COT in the wall pot for about 4 months, but recently moved them into my succulent dish to make it look better and to kinda keep all my succulents in one place. It's basically in the exact same exposure as it was here on the wall, but with a little more direct sunlight as the windows are longer and not obstructed by a roof. So thus again, I have an empty wall pot on the wall. I've tried looking for the other species suggested but found none of those. I guess I've miss judged the sunlight that enters my window as during the summer, almost no direct light enters my room while in late summer/fall/winter/spring, The wall pot plant would get full sun. I was thinking of moving it so it would allow me to plant a peacelily or other in there, but then I'd have a hole in the wall. So now I'm looking again. Are there any other types of plants beside succulents and Cacti that could go well here? The plant has to be a up grower and not trailing as of it were to trail it would trail directly below my window which gradually reduces the light levels. I'd put a sago Palm in it, but the top portion of the pot doesn't seem like a sago with its bulbous base could fit in there.